Getting phantom image perfectly centered


This is driving me nuts! I can't get the image centered unless I turn the balance control on the preamp to the 1:30 position. I've tested the system from source to loudspeakers from an electrical standpoint, so I know each speaker is getting the exact same electrical signal with a test tone and each speaker outputs the same dB with the same test tone.

So, it HAS to be the speaker room interaction, right?

I've read http://www.linkwitzlab.com/listening_room.htm and I THINK I understand everything.

All of the following measurements are in inches:
The room is 189 long by 144 wide. (15.75 feet by 12 feet)

The speakers are precisely 45.5 inches from the back wall.
They are each 26.5 inches from the side walls with a caveat. The left speaker is 27.5 inches from the window sash, which is 1 inch deeper than the wall. It's 30 inches to the top panes of glass and 28 inches from the lower panes of glass. But measured from the actual wall, both speakers are exactly 26.5 inches from the wall.

The speakers are precisely 90.5 inches apart.

The listening position is pretty close to 45.5 inches from the back of the room. The back of the room is open to the rest of the house and the wall on either side of the opening is symmetric with each partial wall being 36 inches.

Listening to a recording were I know the voice is dead center, the voice is actually just to the left of centered, and I mean "just". Would you recommend moving the left loudspeaker towards the center an inch or two?

What kinds of techniques to you use to "dial it in" when you've got a really revealing system and you are past the "math" and it's all more art than strict science?

I think you should be able to see a picture of my listening room here: http://orion.quicksytes.com/download/file.php?id=3096

My apologies if this isn't the right sub-forum to post this question to.
marktrav
I've been in your situation before and it also drove me nuts! What i did was just make sure everything is symmetrical - speaker to listener, centered between both speakers, etc. When you got all that down, play with the toe-in to dial it in. If your image is to the left, start toeing in the left speaker by a couple mm and the right toe out a couple mm. Just do really minor toe-in movements and eventually you will find it like I did. Good Luck!
I'm wondering if reflections off the window are pulling the image to the left.
Could you try putting some pillows or hanging a heavy blanket over the window
just to see if things get better? Maybe room treatments are something to
consider. On the other hand, maybe what you are doing is exactly what a
balance control is for!? though positioning at 1:30 sounds like a little more than
just a little to the left. Another option might be toe-in but I think adjusting the
balance control is better than that and room treatments (see GIK) best of all.

By the way - channel imbalance - whatever the cause makes me crazy. So I feel
your "pain".

Good luck...
The window to the left and sound reflections from that almost certainly has to be a factor resulting n more reflected sound energy to teh left rather than right.

Do you hear a difference if the shade is up or down?
I do hear a bit of difference with the shade down. The image moves ever so slightly to the right, but still left of center.

I ended up moving the speaker TOWARD the window about an inch or so, and into the room about an inch or so, and I now have a centered image and gobs and gobs of depth and layering. Well, I had the depth and layering before, it was just off center. :)

I think eventually I'm going to put some proper wall treatments on the first reflection point of the right speaker and some heavy drapes on the windows and see if I can't put that left speaker back where it was.

In the meantime, I guess I'm ok.

Would it have been better to move both speakers closer to each other to avoid the first reflections? Or was what I did by moving the left speaker further away from center but maintaining distance to the listener (by moving it forward) the best "hack" for now?

I guess whatever works, eh?
I'm in the whatever works camp but do think some room treatments will pay unexpected dividends. By the way - what kind of speakers are those?
Whatever works. Every room is different. Not every setup will have symmetrical acoustics so there is no rule that says your speaker placement must be symmetrical either.

Also all speakers have different dispersion patterns at various frequencies. Its usually a good idea to get a handle on that case by case in order to figure out best placement option faster.

Its always best to avoid early wall reflections for best imaging. The tradeoff is that distance from walls often will lower bass levels. What sounds best always varies case by case. So don't be afraid to experiment and do whatever works. Should not be needed is all is well but having a balance control provides yet another option.
Missed that your system was posted.
To be clear, you tested the components by switching the places of the left and right speakers and the image still skewed to the same side? Speaker imbalances/difference are apt to be more significant than any electrical component. I also presume you tested the overall electrical balance of your system by switching the speaker leads from the amp going to your speakers?

If it is truly room issue, the easiest fix is to use the balance control--just leave it at the 1:30 position--that is what the control is designed to do. I am amazed how many listeners do without a balance control, I find it essential.

The other way balance can be restored is to move one speaker forward by a small amount (I would work with 1/2 inch increments). The closer a speaker gets, the more the image shifts toward that speaker because of higher volume (less fall off of volume because of distance) and because, of a timing change (your brain will interpret the sound coming first from the nearer speaker as an image shift in that direction). I personally don't like skewing the image position a lot by making such a position change, so again, I prefer to just use the balance control.

It is always productive to try changes in speaker placement and placement of your listening chair. But, when doing this, keep in mind that there are other considerations than getting the image to center correctly. Be sure to get the balance of bass frequencies correct and avoid positions that cause sound to wildly change when you make minute changes in your listening position.

Trying to treat the room to cure this problem will not be easy to do. If there is an imbalance in sound arriving from one direction, a big compensating change to absorb some of that energy to "balance" the room will inevitably create tonal changes because it is nearly impossible to uniformly absorb sound energy across all frequencies. The result of such treatment is unpredictable. But, if the problem has to do with standing waves and other such forms of constructive and destructive interference of waves, some treatment, such as bass traps in the corners could be helpful. I would also also try very modest wall treatments, such as putting tapestries on walls, before going wild with specialized room treatments.

Finally, I note that your speakers are quite far apart for your listening position. Even if you toe them in to face much more directly at your listening position, it would be hard to get a very solid sounding middle. If possible, you should at least try moving the speakers much closer together.

Good luck on your experiments.
The speakers are precisely 45.5 inches from the back wall.
They are each 26.5 inches from the side walls with a caveat. The left speaker is 27.5 inches from the window sash, which is 1 inch deeper than the wall. It's 30 inches to the top panes of glass and 28 inches from the lower panes of glass. But measured from the actual wall, both speakers are exactly 26.5 inches from the wall.

The speakers are precisely 90.5 inches apart.

The listening position is pretty close to 45.5 inches from the back of the room.
Larryi, I don't think his speakers are too far apart.
Looking at the photo of his room it looks like he has the speakers setup along the long dimension i.e. along the 189" dimension.
if the speakers are 45.5" from the wall & the listening position is 45.5" from the other wall, then, he should be 98" from the speaker which is little over 8 feet. The speakers are 90.5" apart which is 7.5 feet. I don't think that his speakers are too wide vs. his seating distance.....
maybe you mis-read one or more of the dimensions in his orig post??
Marktrav, real nice system and setup. If the balance control centers the sound image, then don't worry too much about it. That's what balance controls are for. You could also move your listening position by a small amount to achieve a similar effect.

Since your loudspeakers are designed to work with the room I would caution you about the use of acoustic room treatments on the side walls.
There's one part of your system that I don't think you've mentioned having tested: your ears. Not trying to be a wiseguy, but many people have unequal acuity in their left and right ears. Just a thought.
-Bob
Mark, I'm sure you will notice, but I posted a response under your "System".
I recall this question being asked quite some time ago and if I remember correctly, practically all recordings 'lean' to the left side of center. It was a phenomena inherent in the recording process as nothing was really dead center.

Most modern recordings don't exhibit this tendency due to whatever reasons but I think it has to be better recording techniques.

Maybe someone who was active during those days can chime in as to exactly why this was.

All the best,
Nonoise
my first thought was the glass . then what is behind you ? is that a wall , any openings?
yes good point that ears could be part of the problem. An ear cleaning kit is a very cost effective tweak on occasion. 👂👂
Nice system, Marktrav and I'm intrigued by your speakers. I would say there's no doubt that the window is having an effect on the sound imaging.

My advice is leave the setup the way it is temporarily since it now sounds good and contact the company enclosing the pic of your room. It seems like they strive for perfection and and I'm sure somebody can help you tweak your system, especially since you've followed the setup procedure.
It is possible that you have a bit of high frequency loss in the one ear.

A crude but quick test is, rub your fingers together right next to one ear, and then right next to the other. Is the tonal balance exactly the same?

By the way, I use the fingers-rubbing test to gauge ambient sound pressure level. If I can't hear my fingers rubbing together right next to my ear, there's a pair of earplugs in a plastic case in my pants pocket, and unless there's a really compelling reason not to, they go in my ears. I only have one pair of ears and I need them to be fully functional.

Duke
I posted a thread about this a few years back also. I've noticed that the image can shift on me daily and I've attributed this to my ears. Some days my left ear is more clogged up, sometimes it's my right ear. I've made cleaning my ears part of my audio hobby. I also value my hearing more than ever and wear ear plugs at times to protect my hearing (15,000 rpm's and 100mph wind is no good for the ears).

I've found that the bay window in my room accentuates the bass in the same way that bass is louder in the corners of the room.

Since you are so exact with speaker placement you ought to do what I do and attach a string to the center of the headrest on your listening chair and make sure that your speakers are equidistant from the listening position. I've found that to be more critical than the speakers being the exact distance from the walls (someone pointed out to me that rooms aren't perfectly square). You still need to "eye" the placement because they can be equidistant but not equally apart from the centerline. I also use a level to level my speakers.
Thanks for all of the responses so far! As mentioned in my prior post, I moved the left speaker OUT and inch, and using a string (tape measure) moved the left speaker forward until it was equidistant to my ears as the right speaker.

All is well now.

The reason I don't like to use the balance control unless it's absolutely a last resort is that I got it in my head somewhere that it causes a phase shift/imbalance or something to that effect. Perhaps it was a manufacturer's ad that made a big deal out of the fact that the balance control was "out of the circuit" when at the 12 o'clock position.

The speakers are an dipole, active crossover design from Linkwitz Labs that I built myself. The crossover happens before the amps, so each speaker gets a direct amp connection. The dynamics are amazing. Everything is amazing about this speaker, and I'm glad the only issue I've had so far is the center image problem.

I sold a pair of Vienna Acoustics Beethovens powered by a VTL ST-150, so I was a bit worried going down this path, but it wasn't a mistake at all. A friend of mine who owns a pair of Maggies (the smaller ones), says mine sound just as good as his on the upper and mid-range, but my bass is worlds better than his. As the designer says, it creates a magic window to the recording.

My ears are clean and super sensitive, which I wished sometimes they weren't. :) Then I wouldn't have these problems. :)
Making the distance between each speaker and your ears different will cause slight phase shift, particularly at higher frequencies, and unequal toe-in will also have an effect on phase. Changing the relative volume (using the balance control will not have a direct effect on phase relationships.

When adjusting speaker position, like you, I still try to make the speakers equidistant to my head. I have found that a cheap laser rangefinder I picked up at Home Depot to be really handy in this regard.
you state you moved the left speaker in further to compensate for the window making that wall equal to the right . It is the hardness of the glass that is causing the sound waves to reach your ears sooner than from the right side. Try placing something with a more absorptive nature on the sill when listening , perhaps a small piece of sheetrock as a test .
I invite you to check my website myspeakersetup.com and read the speaker setup article. Try not to be so focused on measuring - put your tape measure away and listen with your heart. I would definitely toe the speakers in a little and rake them back some - even if the owners manual says not to.
Time for an audiogram.
"My ears are clean and super sensitive"

That's great! But you don't know whether they are EQUALLY super sensitive unless you've had an audiogram. Simple, painless and usually inexpensive.
-Bob
Marktrav, did you ever swap out the channels, ie connect the left speaker to the right amplifier and right one to the left channel and see what happens? It's simple just swap the speaker cables from one to the other.

2nd, the room picture you supplied isn't clear and doesn't show the whole room but based on what I see there's a soft piece of furniture in front of your right speaker, that must be sucking energy from the right channel. It also looks like the right speaker is sitting on something which I can't make out, what is that?
David
Good to hear that you got it dialed in! By the way, Nice job on the speakers! There is a pair for sale local to me and if I had the $ I would have bought them. Heard them at RMAF 2 years ago and they are awesome. Enjoy!
You have made a lot of measurements but I didn't see the following. Measure from the front of each speaker to the listening position, they should be the exact same length. Make sure if speakers are toed in they have the exact same angle. Good Luck
BMWMCAB - Are you sure toeing IN the left speaker and toeing OUT the right speaker, if the image is leaning left, is correct? Would that not cause the sound from the left speaker to arrive "first" and shift the image even more to the left?
Or maybe (and probably) I'm missing something here. BTW, I've been wrestling with this exact same problem for a while and have found this thread to be (hopefully) somewhat of a Godsend, as my image shift imbalance usually reduces me to writhing on the floor in the fetal position, begging for its induced madness to stop...
Relax...Lindsey Buckingham famously said most stereo recordings are off centered slightly to the left...its the recording... Not your system
Could it be the Coriolis effect? ... maybe the stereo image is a little bit off to the right in the Southern Hemisphere.
Please bear in mind that loudspeaker pair matching can have a tolerance of up to +/-3db although the reality is probably less. Cascade this effect all the way from cartridge through phono stage and power amplifier and it could be even worse if it turns out to be cumulative.
In such cases the only recourse would be to use the balance control. :(

I'm with you though when it comes to avoiding the use of the balance control. I never use it ;^)
Relax...Lindsey Buckingham famously said most stereo recordings are off centered slightly to the left...its the recording... Not your system

Anybody know whether this is really correct (either the actual information about the recording, or that Lindsey Buckingham said it? It's been driving me bat-$hit for the last couple of years. I can compensate easily enough because my pre had separate TVCs for each channel, but still, it seems like such an easy thing to get right.
This is why we need three channel, with a summed center channel. Blame it all on shellac.
Weebeesdad,

That's also what I thought at first but through trial and error, I found that this method actually worked for me. If the image is not perfectly centered, it really bugs the heck out of me and I would try many things to correct it. The up and back method works to a certain point but it hinders the harmonics and tones. Ymmv.
You sir have an issue with your room. Move the speakes all you want but it will still return. That will be eliminated with proper measuring and room treatments. Paying particular attention to the "glass window"! The most likely culprit is your ceiling being untreated. I learned that when I had my room finished using Vicoustics panels throughout the room. In the past there had been trouble locating a clear center image sometimes on playback. Three different sets of speakers, both Electrostatic panels and moving coils have been thru this room. They all did it until I treated the ceiling and walls, especially behind your listening area. Even though it's open there maybe something reflecting behind you causing signal errors. Best of luck to you.
Have you measured tweeter height on both speakers from the floor?I found they need to be exactly the same height,not a half inch off but dead even.My brother was having problems till I went over and found his tweeters were a half inch off,that cleared up his complaints.He also suggested putting some carpet on the one side wall which really made an improvement in my system.Mine are dead on now,perfect,and it costs no money.
I forgot to mention also to check with a level the tops of the speakers so that they are perfectly level with each other.That bubble is dead on exact same on both my speakers.
I found the problem and I feel like an idiot. Remember, these are 4-way active x-o speakers completely built from scratch.

I had mis-wired the polarity of 4" driver from the instructions. I'm not sure how I did that, but I let it go for months chalking it up to bad acoustics, less than top quality electronics, etc. I was starting to wonder if there was another 4" driver that could be substituted because it just sounded brittle in the upper midrange. The upper midrange is why you spend so much money in this hobby! I upgraded to an Ayre QB-9, a Parasound JC-3+ and a few other things. I was about to start considering the amps.

After a glass of wine in a listening session, I just decided to swap the speaker connections on the 4" driver (knowing full well I'd wired it perfectly when I built it!!!! - NOT!) and low and behold, what a glorious sound!

I returned the balance control to the middle position and returned the speakers to their former mirror image of each other and now I'm in heaven. (Again!)

It's funny how good these speakers sounded for the past several months even with that mistake.

I get to enjoy that "new equipment" high all over again. :D